Add another real-life example of setting a quirk for a USB gaming

keyboard.  From forum thread: https://forums.freebsd.org/threads/55717/

MFC after:	1 week

share/man/man4/usb_quirk.4

@@ -16,7 +16,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 26, 2015
+.Dd April 4, 2016
 .Dt USB_QUIRK 4
 .Os
 .Sh NAME
@@ -234,6 +234,12 @@ device which appears as a USB device on
 usbconfig -d ugen0.3 add_quirk UQ_MSC_EJECT_WAIT
 .Ed
 .Pp
+Enable a Holtec/Keep Out F85 gaming keyboard on
+.Pa ugen1.4 :
+.Bd -literal -offset indent
+usbconfig -d ugen1.4 add_quirk UQ_KBD_BOOTPROTO
+.Ed
+.Pp
 To install a quirk at boot time, place one or several lines like the
 following in
 .Xr loader.conf 5 :